Biology subjects

Caldelari, R.

Publications and source records attributed to Caldelari, R..

5 recordsLinked to original sources

bioRxiv2026

Plasmodium berghei liver stages establish a damage-mimicking vacuole to hijack host ER membrane contact site machinery for lipid uptake

Plasmodium liver stage parasites undergo massive intracellular replication and therefore require extensive acquisition of host-derived lipids. How parasites coordinate lipid supply at the host-parasite interface, however, remains poorly understood. Here, we show that the Plasmodium berghei parasitophorous vacuole membrane (PVM) selectively mimics features of damaged endolysosomal membranes, including dynamic LC3-positive membrane tubules and PI4K2A-dependent PI(4)P accumulation, while lacking canonical damage markers including ESCRT components and galectins. This damage-mimicking membrane state drives OSBP recruitment and is associated with formation of VAPA/B-positive ER-PVM membrane contact sites. Disruption of VAPA/B or OSBP impaired PVM integrity and parasite survival, while OSBP depletion reduced cholesterol accumulation at the PVM. Together, our findings suggest that liver stage parasites exploit host lysosome repair-like pathways to redirect host lipids toward parasite growth and intracellular survival. These results redefine the PVM as an active metabolic interface that enables host lipid acquisition rather than merely serving as a protective barrier.

microbiology↗

bioRxiv2025

Post-translational modifications of microtubules are crucial for malaria parasite transmission

Microtubules, composed of - and {beta}-tubulin polymers, are essential components of the eukaryotic cytoskeleton. They maintain cellular shape and structural integrity and play critical roles in cell division and in intracellular vesicular transport. In Plasmodium, the parasite that causes malaria, nuclear replication during the liver stage is among the fastest known in eukaryotic cells and relies heavily on microtubules for DNA segregation and cytoskeletal organization. Despite their importance, the role of microtubules in liver stage development remains largely unexplored. Here, we investigated microtubule dynamics during liver stage development using a combination of cell and molecular biology techniques, expansion microscopy, and live-cell imaging. By employing antibodies specific for -tubulin post-translational modifications (PTMs), we found that the Plasmodium sporozoites subpellicular microtubules (SSPM) persist during liver infection, giving rise to liver stage parasite microtubule bundles (LSPMB). These LSPMB form multimeric tubulin structures within hepatocytes and are redistributed to the hemi-spindle poles of parasite nuclei during schizogony. Deletion of the C-terminal region encompassing all known Plasmodium -tubulin PTM sites prevented sporozoite migration from the mosquito midgut to the salivary glands, effectively blocking parasite transmission. Using Plasmodium microtubule-specific depolymerisation drugs, we found that while LSPMB are stable in sporozoites, they exhibit dynamic behavior during hepatocyte infection. Given the regulatory role of PTMs in microtubule dynamics, we generated parasite mutants by substituting and deleting key -tubulin C-terminal residues involved in PTMs. Substitution of the polyglutamylation site with alanine and deletion of the C-terminal tyrosination/detyrosination motifs impaired parasite growth during liver infection. Together, our findings reveal extensive microtubule remodeling during liver stage development and establish -tubulin C-terminal modifications as critical regulators of both intracellular development and parasite transmission of Plasmodium parasites.

cell biology↗

bioRxiv2023

Host metabolic pathways essential for malaria and related hemoparasites in the infection of nucleated cells

Apicomplexan parasite diseases, including malaria (Plasmodium) and theileriosis (Theileria), pose a significant threat to global health and the socioeconomic well-being of low-income countries. Despite recent advances, the common host metabolic proteins essential for these highly auxotrophic pathogens remain elusive. Here, we present a comprehensive investigation integrating a metabolic model of P. falciparum parasites in hepatocytes and a genome-wide CRISPR screen targeting Theileria schizont-infected macrophages. We reveal unifying host metabolic enzymes critical for the intracellular survival of these related hematozoa. We show that pathways such as host purine and heme biosynthesis are essential for both Theileria survival and Plasmodium liver development, while genes involved in glutathione and polyamine biosynthesis are predicted to be essential for Plasmodium only under certain metabolic conditions. Our work highlights the importance of host porphyrins for the viability of liver-stage Plasmodium. Shared parasite vulnerabilities provide a resource for exploring alternative therapeutic approaches to combat these crippling diseases.

microbiology↗

bioRxiv2022

Small-molecule inhibitors targeting prokaryotic ClpQ protease in Plasmodium display anti-malarial efficacies against blood and liver stages

The ATP-dependent ClpQY system is a prokaryotic proteasome-like machinery in the mitochondrion of malaria parasite, Plasmodium. This protease system is identified as a validated target for malaria intervention. Here we have identified drug-like small chemical compounds, pyrimidotriazine derivatives, as specific inhibitors of P. falciparum ClpQ (PfClpQ) having effective parasiticidal efficacies on asexual and liver stages. Screening of the Malaria Box compound library, using a robust in vitro activity assay, identified a hit compound targeting the PfClpQ protease with IC50 at ~750nM. Further, Structure-Activity Relationship (SAR) analysis, using a small library of derivatives of the hit compound, identified three potential lead compounds, ICGEB-L1, ICGEB-L2 and ICGEB-L3, which inhibited enzyme activity with IC50 in 100-200nM ranges. The three lead compounds effectively inhibited in vitro asexual stage parasite growth in similar concentration ranges with ~100-fold selectivity over mammalian cell line; in addition, these compounds effectively inhibited in vitro growth and maturation of hepatocytic stage parasites with EC50 in low nano-molar ranges. These compounds were found to effectively block the development of trophozoite stages to schizont stage, concurrently arresting development and segregation of parasite mitochondria, in asexual as well as hepatocytic stages of the parasite. These morphological and developmental effects of the drugs on parasites mimic the data from genetic ablation of PfClpQ. Importantly, all three compounds showed significant in vivo anti-parasitic efficacies on blood stages of P. berghei mouse malaria model. Overall these results suggest that these PfClpQ targeting compounds are promising candidates to develop new anti-malarials.

microbiology↗

bioRxiv2019

Transcriptome analysis of Plasmodium berghei during exo-erythrocytic development

The complex life cycle of malaria parasites requires well-orchestrated stage specific gene expression. In the vertebrate host the parasites grow and multiply by schizogony in two different environments: within erythrocytes and within hepatocytes. Whereas erythrocytic parasites are rather well-studied in this respect, relatively little is known about the exo-erythrocytic stages. In an attempt to fill this gap, we performed genome wide RNA-seq analyses of various exo-erythrocytic stages of Plasmodium berghei including sporozoites, samples from a time-course of liver stage development and detached cells, which contain infectious merozoites and represent the final step in exo-erythrocytic development. The analysis represents the completion of the transcriptome of the entire life cycle of P. berghei parasites with temporal detailed analysis of the liver stage allowing segmentation of the transcriptome across the progression of the life cycle. We have used these RNA-seq data from different developmental stages to cluster genes with similar expression profiles, in order to infer their functions. A comparison with published data of other parasite stages confirmed stage-specific gene expression and revealed numerous genes that are expressed differentially in blood and exo-erythrocytic stages. One of the most exo-erythrocytic stage-specific genes was PBANKA_1003900, which has previously been annotated as a "gametocyte specific protein". The promoter of this gene drove high GFP expression in exo-erythrocytic stages, confirming its expression profile seen by RNA-seq. The comparative analysis of the genome wide mRNA expression profiles of erythrocytic and different exo-erythrocytic stages improves our understanding of gene regulation of Plasmodium parasites and can be used to model exo-erythrocytic stage metabolic networks and identify differences in metabolic processes during schizogony in erythrocytes and hepatocytes.

microbiology↗